1. Field of the Invention
The present invention relates to a curved belt conveyor.
2. Description of the Related Art
In a curved belt conveyor, a conveyor belt or continuous belt matched to a curve shape is usually driven in a circumferential, or continuous, manner by guiding the continuous belt around return rollers, the rotation axes of the return rollers being arranged at an angle with respect to each other. Here, at least one return roller is driven, so that a load-bearing upper strand of the continuous belt travels in the conveying direction, whereas a lower strand travels in the opposite direction on a lower side. A good to be conveyed, which is placed on the continuous belt, can thereby be conveyed around a curve. Mostly, curve angles of 90° or 180° are realized by means of several curve segments of driven continuous belts.
By the rotation axes of the return rollers being arranged at an angle with respect to each other, the forces acting on the continuous belt due to the drive have a component transverse to the conveying direction. These forces transverse to the conveying direction pull the continuous belt on the return rollers toward the curve inner side.
In order to prevent the continuous belt from slipping toward the curve inner side, the curve outer edge of the continuous belt can be circumferentially, or continuously, provided with a V-belt on the side facing toward the rollers, according to WO 2009/141157 A. Tensioning rollers arranged along the curve outer frame of the curved belt conveyor are engaged with the beveled side surfaces of the V-belt and apply a support force to the continuous belt to keep the continuous belt in position. In order to prevent the V-belt from coming off the tensioning rollers, additional pressing rollers or keeping down devices per tensioning roller have to be provided, which press down the continuous belt in the region of the V-belt from above, i.e. from the side facing away from the return rollers. These pressing rollers project from the curve outer frame of the curved belt conveyor and reduce the usable conveying area of the continuous belt.
According to EP 1 529 008 B1, disturbing tensioning devices at the curve outer frame of the curved belt conveyor can be avoided by making an area of the return rollers crowned, or by arranging additional guide rollers between adjacent belt rollers in the lower strand in order to apply the necessary support forces for the continuous belt. Thus, the entire surface of the continuous belt becomes usable. However, with such a construction, only small curve angles per continuous belt can be realized due to the support force to be applied.
Thus, it is the object of the present invention to provide a curved belt conveyor that allows using the entire bearing area of the continuous belt at large curve angles per continuous belt.
This object is solved by a curved belt conveyor according to the independent claim. Preferred embodiments are defined in the dependent claims.